It sounds like you are trying to insert a code fragement. Here are the
instructions from Publisher Help:

On the Insert menu, click HTML Code Fragment.
Click the place on your Web page where you want the HTML code fragment to
appear. (Note that if you are working in an existing text box, you need to
click on the page outside that text box. You cannot insert the HTML code
within a text box.)
-Or-
Position the mouse pointer where you want a corner of the HTML code fragment
frame to appear, click, and then drag the mouse diagonally.
The HTML Code Fragment Properties dialog box appears.
In the HTML Code Fragment box, insert your HTML code fragment by typing or
pasting from another source over the entire placeholder text. (Sometimes in
Publisher you may need to use Ctrl + V, in order to paste.)
Click OK.
Your code fragment appears as code in the frame on your Web page, and the
result of your code fragment appears when you preview or publish your Web
page.

If this does not address your issue, please post back.

DavidF